In a high density digital magnetic recording on a magnetic medium such as a magnetic tape, a magnetic card, a disc, a drum, or the like, there are generally a number of tracks which are relatively narrow and which are relatively closely spaced to one another. If the magnetic medium becomes damaged after the information is recorded as, for example, by dirt particles, by abrasion, or by other means, portions of the recorded information may be sufficiently obliterated that they cannot be read. An example of damage caused in these ways has been found to be scratches which extend at an angle to the track direction and which may obliterate or otherwise make illegible one or more of the recorded binary digits (bits) along the track.
The object of this invention is to provide, in a magnetic recording system, a means for recovering a large fraction of the otherwise illegible recorded information discussed above.